1. Field of the Invention
The present invention relates to a deadbolt lock with an electronic touch-key, and particularly to a deadbolt lock having an electronic touch-key containing a microcomputer chip that exchanges a security code with a microcomputer contained within the deadbolt lock housing to unlock the deadbolt.
2. Description of the Related Art
Deadbolt locks are commonly and widely used in residential homes, apartments, commercial buildings, and other settings where it is desired to secure an entry against unwanted intrusion. Deadbolt locks are used in some instances as the sole means to lock an entry door, and in other instances in conjunction with other locking mechanisms. Traditional deadbolt locks employ a mechanism that includes a set of internal tumblers that must engage with the teeth formed in a conventional key to open the lock. A key that relies on the mechanical interaction of its shape with the tumblers of a lock can be readily copied. The security provided by conventional locks can be jeopardized when duplicate keys, that might be maintained by an apartment or rental building manager or retained by a dwelling's previous owner, exist and can be copied. Additionally, a person with a locksmith's skills may be able to “read” the tumblers of a lock with a set of locksmith's tools and create a suitable key without even the need for an original key to copy.
As owners and tenants of a dwelling come and go, it is often necessary and desirable to change the locks to ensure that old keys that may be retained by old occupants are no longer functional. In residential homes, this task is an inconvenience. In apartment complexes, where there may be a large turnover in occupants, this may become costly. For a hotel, this cost is prohibitive. In any environment where a building manager or maintenance team has a set of duplicate keys or a master key even the safeguard of changing locks cannot entirely eliminate the security threat of duplicate keys.
Electronically keyed locks have been employed to solve these problems. Electronic locks have incorporated card readers, keypads, remote control devices, and other methods to achieve greater security and flexibility in re-keying. Among the electronic devices that have been used to activate door locks are electronic touch-keys, which are typically devices wherein a microcomputer chip is housed within a case and is activated on contact with a reader. A deadbolt lock using an electronic touch-key, that would provide enhanced security and solve problems inherent with duplicate keys and re-keying expense and effort, presents particular challenges of power consumption, size, and complexity. In battery-powered solutions battery life plays a significant role, and when excessive power is used the device will require excessive maintenance to replace the batteries. Some electronic lock assemblies are simply too large to allow a quick retrofit by simply replacing a conventional lock with the new device. Numerous efforts to produce an electronically keyed door lock have been handicapped by such shortcomings.
The U.S. Patent Publication No. 2001/0028299, published October, 2001, discloses an electronic key assembly working in conjunction with a deadbolt lock. The electronic key disclosed is a touch-key device incorporated into a housing having the general shape and form of a conventional key. A small computer chip is enclosed in the head of the key assembly. A data contact protrudes from the front of the key head so that, when the key blade is inserted into the lock, the data contact engages with a matching data contact on the lock adjacent to the key slot. The computer chip exchanges a security code with a microprocessor contained within the lock and, when a valid security code is received, the microprocessor commands a solenoid mechanism to unlock the lock. The solenoid plunger, or a plate that is operated by the solenoid plunger, is engaged to or disengaged from the lock cylinder plug to prevent or allow rotation of the cylinder plug. When the plunger or plate is disengaged from the cylinder plug, thereby allowing its rotation, the mechanism is unlocked. A weakness of this arrangement is that, because the mechanism is unlocked when the solenoid is energized, there is a continuous current drain while the lock is maintained in its unlocked state. Thus, the life of batteries used for power cannot be maximized. Additionally, because the lock relies on the plunger or plate to physically engage with the cylinder to prevent rotation, application of excessive turning force while the lock is locked could damage the lock or overcome the locking mechanism and allow unauthorized entry.
The U.S. Pat. No. 5,437,174, issued on Aug. 1, 1995 to K. Aydin, discloses another electronic lock system that uses an electronic touch-key to activate a locking/unlocking mechanism. The locking/unlocking mechanism, activated into the unlocked position by the exchange of a security code between the electronics key and an internal microprocessor circuit, uses an electric motor to cause a plunger to engage with or disengage from a cavity in the lock cylinder. This arrangement allows the lock to remain in either the locked or unlocked state without continued current drain from the batteries. However, the motor assembly is rather bulky and requires that a door be modified to accommodate the lock assembly. Rather than fitting a single round hole typically required to accommodate a door lock assembly, an additional hole must be drilled through the door to accommodate the motor assembly. This increases the cost and complexity of the lock's installation, and eliminates the possibility that the electronic lock can be easily retrofitted in place of an existing door lock without further modification of the door.
U.S. Pat. No. 5,923,264, issued on Jul. 13, 1999, to G. E. Lavelle et al., shows an electronic lock system that incorporates an electronic touch-key along with alternate access code readers. Such an alternate access code reader might be a keypad where an access code could be manually entered. The lock is responsive to any of its access code readers. The lock assembly as shown includes a combined keypad and touch-key reader panel that is entirely separate from the door lock and handle mechanism itself. Further, a second separate housing is required for the electronic circuitry. The keypad and touch-key reader panel is shown on the opposite side of the door from the electronics housing, requiring an extra hole to be drilled through the door to allow for the electrical connections necessary between components. This lock fails to provide for an easy retrofit by simply replacing a door's existing lock.
The Chinese patent CN2441930 of Zhang, one of the co-inventors of the present invention, published on Aug. 8, 2001, describes an axial clutch mechanism.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus a deadbolt lock with an electronic touch-key solving the aforementioned problems is desired.